U.S. patent application number 15/021823 was filed with the patent office on 2016-08-04 for vascular implant.
The applicant listed for this patent is UCL BUSINESS PLC. Invention is credited to Gaetano BURRIESCI, Michael John MULLEN, Alexander SEIFALIAN, Spyridon TZAMTZIS, John YAP.
Application Number | 20160220366 15/021823 |
Document ID | / |
Family ID | 49552643 |
Filed Date | 2016-08-04 |
United States Patent
Application |
20160220366 |
Kind Code |
A1 |
BURRIESCI; Gaetano ; et
al. |
August 4, 2016 |
VASCULAR IMPLANT
Abstract
A vascular implant comprises a structure defining a flow
passage, the flow passage having a first end and a second end. The
vascular implant is also provided with a skirt around at least a
portion of the outer periphery of the structure. A portion of the
skirt is fixed to the structure to form a seal with respect to the
flow passage. The skirt is compliant such that, in response to a
higher fluid pressure at one of the ends of the flow passage, the
skirt is configured to be urged against the anatomy at the site in
which the implant is located, to span between the outer periphery
of the structure and said anatomy.
Inventors: |
BURRIESCI; Gaetano; (London,
GB) ; TZAMTZIS; Spyridon; (London, GB) ;
MULLEN; Michael John; (London, GB) ; SEIFALIAN;
Alexander; (London, GB) ; YAP; John; (London,
GB) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
UCL BUSINESS PLC |
London |
|
GB |
|
|
Family ID: |
49552643 |
Appl. No.: |
15/021823 |
Filed: |
September 12, 2014 |
PCT Filed: |
September 12, 2014 |
PCT NO: |
PCT/GB2014/052785 |
371 Date: |
March 14, 2016 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
A61F 2230/0069 20130101;
A61F 2250/0069 20130101; A61F 2/2475 20130101; A61F 2/2409
20130101; A61F 2/2418 20130101 |
International
Class: |
A61F 2/24 20060101
A61F002/24 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 13, 2013 |
GB |
1316349.8 |
Claims
1-9. (canceled)
10. A vascular implant comprising: a structure defining a flow
passage, the flow passage having a first end and a second end; and
a skirt around at least a portion of the outer periphery of the
structure, wherein a portion of the skirt is fixed to the structure
to form a seal with respect to the flow passage, and wherein the
skirt is compliant such that, in response to a higher fluid
pressure at one of the ends of the flow passage, the skirt is
configured to be urged against the anatomy at the site in which the
implant is located, to span between the outer periphery of the
structure and said anatomy.
11. An implant according to claim 10 configured such that fluid can
enter between the outer periphery of the structure and the skirt to
urge the skirt outward against said anatomy.
12. An implant according to claim 10, wherein the skirt is formed
of a membrane.
13. An implant according to claim 10, wherein the skirt is made of
at least one of: biological tissue, polymer, or fabric.
14. An implant according to claim 10, wherein said portion of the
skirt fixed to the structure comprises a first edge of the skirt
that is sealed with respect to the flow passage around the complete
circumference of the structure.
15. An implant according to claim 10, wherein an edge of the skirt,
separate from said portion that is fixed to the structure, is also
attached at one or more locations around the structure.
16. An implant according to claim 10, wherein the flow passage
contains a valve permitting flow in a direction from the first end
to the second end, and restricting flow in the reverse direction,
and wherein when the fluid pressure at the second end is higher
than the fluid pressure at the first end, the skirt is urged
against the surrounding anatomy at the implant site to restrict
paravalvular leakage.
17. An implant according to claim 16 which is a prosthetic heart
valve.
18. An implant according to claim 10, comprising a plurality of
skirts arranged around the outer periphery of the structure.
Description
[0001] The present invention relates to a vascular implant, such
as, but not limited to, a prosthetic heart valve.
[0002] Prosthetic heart valves have been an area of considerable
research in recent years. Typically, the prosthetic valve comprises
two elements: a support structure comprising a generally tubular
framework surrounding a flow passage; and a flow control structure
provided in the lumen of the support structure and providing the
one-way valve action to permit blood flow in one direction through
the valve, but preventing blood flow in the reverse direction.
[0003] However, a major problem with such implants has been the
occurrence of mild to moderate paravalvular leakage. This can be
particularly severe in the case of sutureless, percutaneous and
transcatheter valves, that are not typically sutured to the host
tissues, for which leakage has been shown to drastically reduce the
hemodynamic efficiency of the valve. This can result in a
significant increase in the load on the heart because any blood
that leaks in the reverse flow direction, around the closed valve,
does not contribute to the useful circulatory output of the
heart.
[0004] Various proposals have been put forward to attempt to pack
material to seal between the outside of the valve and the
surrounding anatomy, but have not been entirely satisfactory, which
is a problem.
[0005] A further problem is that it is undesirable for the implant
to apply a high radial force to the surrounding anatomy to attempt
to form a seal to avoid paravalvular leakage.
[0006] Another problem is that it is desirable for implants to be
retrievable, so any sealing means that permanently hooks into the
surrounding anatomy cannot achieve this.
[0007] The present invention seeks to alleviate, at least
partially, some or any of the above problems.
[0008] The present invention provides a vascular implant
comprising: [0009] a structure defining a flow passage, the flow
passage having a first end and a second end; and [0010] a skirt
around at least a portion of the outer periphery of the structure,
[0011] wherein a portion of the skirt is fixed to the structure to
form a seal with respect to the flow passage, and [0012] wherein
the skirt is compliant such that, in response to a higher fluid
pressure at one of the ends of the flow passage, the skirt is
configured to be urged against the anatomy at the site in which the
implant is located, to span between the outer periphery of the
structure and said anatomy.
[0013] Embodiments of the invention will now be described, by way
of example only, with reference to the accompanying drawings in
which:
[0014] FIG. 1 is a schematic cross-section of an implanted valve to
illustrate its operation as an embodiment of a vascular implant
according to the invention;
[0015] FIGS. 2 and 3 are illustrations of a prosthetic heart valve
of another embodiment of the invention; and
[0016] FIG. 4 shows the heart valve of FIGS. 2 and 3 implanted at
the location of the aortic valve.
[0017] An embodiment of the invention comprising an implantable
valve will now be described with reference to the schematic
cross-section shown in FIG. 1. In this embodiment, the implant
comprises a structure 10 defining a flow passage 12 having a first
end 12A and a second end 12B. The structure 10 sits within the
native anatomy 14. The structure 10 is generally approximately
cylindrical, but in FIG. 1 is, of course, shown in longitudinal
cross-section. The structure 10 typically comprises a framework
made from a metal tube or wire, but may take any suitable form
known in the art.
[0018] The structure 10 supports a flow control device, in this
case a valve comprising valve leaflets 16 located in the lumen of
the flow passage 12. Such valves are well known in the art, and can
comprise one, two, three or more leaflets 16.
[0019] According to preferred embodiments of the invention, the
implant can be, for example, a prosthetic heart valve, such as an
aortic valve, pulmonary valve, mitral valve or tricuspid valve.
[0020] In normal operation, fluid, in this embodiment blood, can
flow from the first end 12A to the second end 12B of the flow
passage 12 in the direction indicated by the arrow A because the
leaflets 16 are flexible and the leaflets separate to permit flow.
Flow in the reverse direction indicated by the arrow B is prevented
by the closure by the leaflets 16.
[0021] However, with conventional devices, it may be possible for
paravalvular leakage to occur by flow of fluid around the exterior
of the structure 10 where there are any gaps between the structure
and the native anatomy. In FIG. 1, the clearance between the
structure 10 and the native anatomy 14 is shown exaggerated for
clarity. In practice, the implant will fit much more snugly in the
implant site (which also helps anchor the implant in place).
However, conventionally, some leakage may be unavoidable due to
natural irregularities in the native anatomy and the inability to
form a perfect seal all the way round.
[0022] As illustrated in FIG. 1, this embodiment of the present
invention provides a skirt 18 around the outer periphery of the
structure 10. The skirt 18 may also be described as a flap, wing,
parachute or similar. The skirt 18 is fixed to the structure 10 at
a joining line 20 such that it forms a seal with respect to the
flow passage 12.
[0023] The joining line 20 can lie in a plane, as in this
embodiment, or can take other shapes, regular or irregular. The
skirt 18 and the joining line 20 are not limited to being in the
particular location relative to the structure 10 illustrated in
FIG. 1, but could, for example, be adjacent to the leaflets 16, or
could be positioned at either extreme end of the structure 10 or
any intermediate position. If the joining line 20 is adjacent to
the end of the structure 10 at the second end 12B of the flow
passage 12, then the skirt 18 will extend beyond the end of the
structure 10.
[0024] The skirt 18 is compliant, for example being made of a
flexible membrane. Suitable material for the skirt 18 includes
biological tissue, polymer, fabric, or a combination thereof. For
example, the skirt can be entirely synthetic, formed from
artificial polymeric material, or can be biologically-derived, for
example a xenograft of bovine pericardium or porcine pericardium,
or a combination of synthetic and biologically-derived material.
Any other bio-compatible material suitable to be formed into a
membrane could be used. The skirt is substantially impermeable to
prevent flow of the relevant fluid therethrough, or becomes
impermeable after the implant, for example due to thrombus coating
or cell proliferation. Although the skirt 18 is flexible, it can be
elastic or inelastic. The skirt 18 is fixed to the structure 10 by
any suitable technique, such as gluing or suturing or by being made
as an integral component of the implant.
[0025] FIG. 1 illustrates the situation in which the fluid pressure
at the second end of the flow passage 12B is higher than the fluid
pressure at the first end of the flow passage 12A. In this case the
leaflets 16 of the valve are urged together so that the valve is
closed and reverse flow through the flow passage is prevented. If
the implant is a replacement aortic valve or pulmonary valve, with
the first end 12A at the left or right ventricle, respectively, and
the second end 12B at the aorta or pulmonary artery, respectively,
then this situation occurs during diastole when the pressure in the
outlet artery rises above the ventricular pressure. If the implant
is a mitral valve or tricuspid valve, with the first end 12A in the
respective atrium and the second end 12B in the respective
ventricle, then this situation occurs during systole, when the
ventricular pressure exceeds the atrial pressure.
[0026] The higher pressure at the end 12B can cause blood to flow
around the implant where there are any gaps between it and the
native anatomy 14. The fluid pressure then urges the skirt 18
against the native anatomy 14, as indicated by the small arrows in
FIG. 1. This engages the skirt 18 against the anatomy at the
implant site and occludes any gaps, and results in a seal against
leakage. In effect, the skirt 18 acts like a parachute that becomes
inflated when there is back pressure against the valve.
[0027] The compliance of the material of the skirt 18 means that it
can conform to irregularities in the anatomy 14 at the location of
the implant. The design of the skirt 18 means that damage to the
native anatomy due to excessive radial force is avoided because the
force urging the skirt into sealing engagement against the native
anatomy 14 is provided by the fluid pressure to which the anatomy
would be subjected to anyway in the absence of the implant.
[0028] A further specific embodiment of an implant according to the
invention is illustrated in FIGS. 2, 3 and 4. Parts corresponding
to those illustrated in FIG. 1 are indicated with corresponding
reference numerals, and so repetition of the description of those
will be avoided.
[0029] The implant of FIGS. 2 to 4 is a self-expanding prosthetic
aortic valve. Further details of its structure can be obtained from
WO 2010/112844. The implant has the addition of the skirt 18. As
illustrated in FIGS. 2 and 3, the joining line 20 at the closed
edge of the skirt 18 where it is fixed to the structure, is curved
such that it is scalloped.
[0030] In this embodiment, the open edge 22 of the skirt 18 is
fixed at one or more points 24 to the structure 10. This prevents
complete reversal of the skirt, either when in use, or when being
implanted. Fixing points 24 still enable the skirt 18 to "inflate"
like a parachute to seal against the anatomy 14, as illustrated in
FIG. 4. FIG. 4 also illustrates that a part of the anatomy around
the implant site can be a native valve leaflet 14.1 that is
displaced when the prosthetic valve is implanted.
[0031] Although a specific implant is illustrated in FIGS. 2 to 4,
which is delivered percutaneously by trans-catheter techniques, the
invention is not limited to those particular aspects. The implant
in this particular embodiment is self-expanding, but it could
equally be expandable or of fixed size.
[0032] Although the embodiments described have a single skirt 18
that surrounds the entire implant, an alternative is to have one or
more individual skirts. The skirts could, in combination, surround
the entire circumference of the implant, either with or without
overlap. Alternatively, the or each skirt could be provided only at
particular positions that are susceptible to leakage.
* * * * *